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Population differences in benzodiazepine sensitive male scent-induced analgesia in the deer mouse, Peromyscus
1Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
Abstract:
We compared opioid and nonopioid involvement in the mediation of scent-induced analgesia in two populations of deer mice, Peromyscus maniculatus; P. m. artemisiae from a mainland region and P. m. angustus from a small marine island. Exposure to bedding taken from the soiled home cage of an isolated (dominant aggressive) male resident elicited a significant increase in the nociceptive responses of male deer mice from mixed sex pairs, with the island population of mice displaying significantly greater analgesic responses than the mainland animals. In the mainland population of mice, the large amplitude analgesia induced by the scent of a conspecific was insensitive to the opiate antagonist, naloxone, but could be blocked by either the benzodiazepine antagonist, Ro 15-1788, or agonist, diazepam. Exposure to the scent of individuals from the island population elicited a lower amplitude analgesia that was sensitive to both the opiate and benzodiazepine manipulations. In the island population, both the lower amplitude analgesia induced by the scent of a conspecific and the higher amplitude analgesic elicited by the scent of a mainland animal was blocked by naloxone and only partially reduced by the benzodiazepine manipulations. Bedding treated with the peppermint also induced analgesia, with the island mice displaying a markedly greater analgesic response than the mainland animals. In both populations of deer mice the peppermint-induced analgesia was blocked by naloxone and insensitive to the benzodiazepine manipulations. These findings are considered in terms of their possible ecological significance and relations to the differences in agonistic and social behaviors between island and mainland populations of deer mice and other small rodents.
Insights
Deer mice exhibit scent-induced analgesia, with island populations showing greater pain relief. Opioid and non-opioid pathways mediate this response, varying between mainland and island mice.
Area of Science:
- Behavioral neuroscience
- Animal behavior
- Pain research
Background:
- Scent cues can influence physiological responses, including pain perception.
- Deer mice populations (Peromyscus maniculatus) on mainland and islands exhibit behavioral differences.
- Opioid and non-opioid systems are known mediators of analgesia.
Purpose of the Study:
- To compare opioid and non-opioid involvement in scent-induced analgesia in two deer mouse populations.
- To investigate population-specific differences in analgesic responses to conspecific and peppermint scents.
- To explore the ecological significance of these analgesic mechanisms.
Main Methods:
- Comparing analgesic responses to conspecific and peppermint scents in mainland and island deer mice.
- Administering opioid (naloxone) and benzodiazepine (Ro 15-1788, diazepam) antagonists/agonists.
- Measuring nociceptive responses to assess the degree of analgesia.
Main Results:
- Island deer mice showed significantly greater analgesic responses to conspecific scent than mainland mice.
- Mainland mice's analgesia was mediated by benzodiazepine pathways, not opioids.
- Island mice's analgesia was sensitive to both opioid and benzodiazepine manipulations, and peppermint scent induced naloxone-sensitive analgesia.
Conclusions:
- Scent-induced analgesia mechanisms differ between mainland and island deer mouse populations.
- Ecological factors and social behaviors likely influence the evolution of these distinct analgesic pathways.
- Opioid and non-opioid systems play complex, population-specific roles in mediating pain relief through olfactory cues.